1. Field of the Invention
The present invention relates to a supporting structure for a vibrator, and particularly, to a supporting structure for a vibrator used, for example, in a vibratory gyroscope for detecting a rotational angular velocity.
2. Description of the Prior Art
FIG. 11 is a perspective view showing an example of a conventional vibratory gyroscope which is a background of the present invention, and FIG. 12 is a front view thereof. The vibratory gyroscope includes a vibrator 2, which includes, for example, a regular triangular prism-shaped vibrating body 3. On approximate centers of three side faces of the vibrating body 3, piezoelectric elements 4a, 4b and 4c are formed respectively.
To the vicinity of nodal points of the vibrator 2, two U-shaped supporting members 5a and 5b are secured respectively. In this case, center portions of the supporting members 5a and 5b are fixed to one ledge-line portion of the vibrating body 3.
Meanwhile, both ends of one supporting member 5a are fixed to one mounting board 6a, and both ends of the other supporting member 5b are fixed to another mounting board 6b. The mounting boards 6a and 6b are respectively bonded to a supporting base (not shown) such as a work plate via a cushioning material (not shown).
In the vibratory gyroscope 1, a driving signal is applied to the piezoelectric elements 4a and 4b or to the piezoelectric element 4c. Thereby, the vibrating body 3 bends and vibrates in the direction (x-axis direction) perpendicular to the face whereon the piezoelectric element 4c is formed. When the vibrating body 3 rotates about the center axis (z-axis) in this state, the bending and vibrating direction is changed by a Coriolis force, and a difference is produced in output signals of the piezoelectric elements 4a and 4b. Thus, a rotational angular velocity can be detected by measuring an output voltage difference between the piezoelectric elements 4a and 4b.
In the vibratory gyroscope 1, though the two supporting members 5a and 5b bend as the vibrator 2 vibrates, since the supporting members 5a and 5b are respectively fixed to the supporting base via the cushioning material and so on, the supporting members 5a and 5b hardly interfere with each other. Thus, the vibration of the vibrator 2 is hardly suppressed by the supporting members 5a and 5b, it can be expected to secure a stable vibrating attitude of the vibrator 2.
However, in the vibratory gyroscope 1, the supporting members 5a and 5b are susceptible to a widthwise direction (y-axis direction) of the vibrator 2, and sometimes the supporting members 5a and 5b deflect in the y-axis direction of the vibrator 2 by an expansion or a contraction of the vibrator 2 due to temperature change. In this case, there is a case where a rotational angular velocity can not be detected accurately.
Furthermore, in the vibratory gyroscope 1, when an impact is applied in the lengthwise direction (z-axis direction) of the vibrator 2 by, for example, dropping down, as shown in FIG. 13, the center portions of the supporting members 5a and 5b bend, there is a case where a rotational angular velocity can not be detected accurately.